Third Generation Partnership Project 2 (3GPP2) Code Division Multiple Access (CDMA), known as 3GPP2 cdma2000, networks support concurrent services functionality for packet data and circuit switched voice communication. The original system supports packet data and circuit switched voice communication and is commonly referred to as the cdma2000 1X system or the 3G1X system. The cdma2000 1X system air interface is standardized in 3GPP2 document C.S0001 through C.S0005 and corresponding Telecommunication Industry Associates (TIA) standard TIA-2000. In addition, new packet data standards, such as cdma2000 High Rate Packet Data (cdma2000 HRPD) have been created. The cdma2000 HRPD air interface is standardized in 3GPP2 documents C.S0024-A and C.S0063.
To provide communication continuity for a wireless unit moving between overlaid 1x and packet data networks, it is desirable to provide cross-paging capabilities that enable the wireless unit to be notified of incoming 1x circuit voice calls when the unit is operating on the HRPD network and that notify the unit of incoming packet data in the HRPD packet data network when the unit is operating on the 1X network. U.S. patent application publication no. 2004/0120283 can be referenced for a description of certain aspects of cross-paging functionality. A 3GPP2 architecture which supports cross paging typically includes a Mobile Switching Center (MSC), a 1x BS (Base Station), an HRPD AN (Access Network or Access Node), an HRPD PCF (Packet Control Function), and a Packet Data Serving Node (PDSN) and is standardized for two different RAN architectures in 3GPP2, A.S0008-A and A.S0009.
Hybrid Access Terminals (HATs) are capable of supporting both the 3G1x and HRPD air interface technologies. In a joint circuit switched, packet switched communication network, such as the 3GPP2 3G1x-HRPD network (in which the 3G1x network provides circuit switched voice support and the HRPD network provides packet switched service), cross paging is used to page a HAT on the network where it is currently monitoring a forward link channel. Thus, cross paging is used to inform the HAT of a call on another network where the HAT is registered for service but not currently monitoring a forward link channel.
When a HAT is paged for service on a second network via a first network, it releases any active call on the first network and begins monitoring a forward link on the second network, from which it is being paged, to complete the call. For example, a HAT may be paged for circuit voice service from the 3G1x network while the HAT is in the HRPD network, currently engaged in an active packet data call. Alternatively, the HAT may be paged for packet data service from the HRPD network while in the 3G1x network monitoring a forward link channel.
When a HAT is cross paged for service in another network, a condition known as ‘ghost ring’ may occur. A ‘ghost ring’ occurs when the HAT responds to a page from a second network while in the first network, terminates any active call in the first network, and attempts to initiate the new call for which it was paged but fails because network resources required to support the call (e.g., air traffic channels or network bearer connections) are not available in the second network (even though they may have been available when the HAT was originally paged, as may occur in networks operating at or near full capacity). When such a scenario occurs, not only does the HAT fail to successfully initiate the call in the second network, but it also may have dropped an existing call in the first network to receive the new call. Generally, then, this is a problem in cross paging architectures where each RAN independently manages its network resources.
FIG. 1 is a signaling flow diagram 10 depicting, in accordance with the prior art (see the 3GPP2-A.S0008-A standard, May 2005 V&V version), a HAT being paged for HRPD packet data service via a 1x network air interface while the HAT is engaged in a circuit voice call. The HAT is registered in the 1x system and on a traffic channel when packet data for the HAT arrives at the HRPD AN/PCF supporting the HAT's packet data session in the packet data network. The arrival of data at the HRPD access network triggers an HRPD cross page in the 1x network.
In prior art signaling 11, it is assumed that, when the HAT arrives on the HRPD network after releasing its circuit call, a connection will successfully be established between the HAT and the HRPD network. However, if for any reason the connection fails to be established due to a lack of network resources, not only will the new call fail to be delivered in the HRPD network, but the 1x circuit call will also have been unnecessarily dropped.
Operators are beginning to deploy Voice over Internet Protocol (VoIP) and Video Telephony (VT) on their HRPD packet data networks and will rely on cross paging to page HATs for packet data service in the 3G1X circuit network. Therefore, a need exists to increase the cross-paging call success rate in joint networks such as the 3GPP2 3G1X-HRPD communication networks.
Specific embodiments of the present invention are disclosed below with reference to FIGS. 2-12. Both the description and the illustrations have been drafted with the intent to enhance understanding. For example, the dimensions of some of the figure elements may be exaggerated relative to other elements, and well-known elements that are beneficial or even necessary to a commercially successful implementation may not be depicted so that a less obstructed and a more clear presentation of embodiments may be achieved. In addition, although the signaling flow diagrams above are described and shown with reference to specific signaling in a specific order, some of this signaling may be omitted or some may be combined, sub-divided, or reordered without departing from the scope of the claims. Thus, unless specifically indicated, the order and grouping of signaling is not a limitation of other embodiments that may lie within the scope of the claims
Simplicity and clarity in both illustration and description are sought to effectively enable a person of skill in the art to make, use, and best practice the present invention in view of what is already known in the art. One of skill in the art will appreciate that various modifications and changes may be made to the specific embodiments described below without departing from the spirit and scope of the present invention. Thus, the specification and drawings are to be regarded as illustrative and exemplary rather than restrictive or all-encompassing, and all such modifications to the specific embodiments described below are intended to be included within the scope of the present invention.